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Colorado: Dillon Reservoir may come close to filling this year

Wet spring brightens water picture

Will Dillon Reservoir fill this summer? Bob Berwyn photo.

Will Dillon Reservoir refill this summer? Bob Berwyn photo.

By Bob Berwyn

FRISCO — With the Roberts Tunnel turned off and Summit County’s streams starting to surge with runoff, the water level in Dillon Reservoir has already come up about two feet since May 1, according to Denver Water’s Bob Peters, who recently issued the latest update for Denver Water’s storage and diversion system.

The Roberts Tunnel is used to shunt water from the Upper Blue Basin beneath the Continental Divide and into the South Platte Basin, where it can be stored in other reservoirs until its needed for municipal use in Denver Water’s service area.

With average precipitation the next few weeks, Denver Water anticipates that Dillon Reservoir will peak at an elevation of about 9,010 feet sometime in July. That’s about seven feet below a complete fill, equal to about 235,000 acre feet. If wet weather continues through May, the reservoir could fill completely in July, rising to 9,017 feet, equal to about 257,000 acre feet. Continue reading

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Colorado: Snowmaking impacts Snake River flows

Massive Snake River snowmaking diversions means tough times for trout after drought summer

This year’s snowpack is well below average and tracking just barely above last year’s.

By Bob Berwyn

SUMMIT COUNTY — The most recent snowstorm helped boost the overall Colorado snowpack just a bit, bringing it on par with last year’s level at this time, which is still well below average for mid-November. Statewide, the snowpack was at 57 percent of average, as of Nov. 15, with most West Slope basins between 50 and 60 percent of average. Even the North Platte drainage, which has seen some significant snows in the Never Summer Range, is only at 64 percent of average.

In Summit and Eagle counties, many streams are flowing at or below historic low levels, creating challenges for some ski areas that rely on direct stream diversions for snowmaking. Keystone, for example, has had to dial back its snow guns several times in the past week as the Snake River dropped to a flow of just six cubic feet per second, the minimum required under state regulations. Continue reading

Colorado: Roberts Tunnel turns 50 this year

23.3-mile aqueduct the key to Front Range development

On February 24, 1960, Roberts Tunnel construction crews from east and west “hole through” and meet. View is from the grant heading toward the east portal. Photo courtesy Denver Water.

By Bob Berwyn

SUMMIT COUNTY — As much as we here in the high country like to grumble about “our” water going to the Front Range, the diversions are one of those facts of life that isn’t going to change anytime soon.

And while Dillon Reservoir is the visible symbol of that reality, that water wouldn’t be going anywhere without the Harold D. Roberts Tunnel, a 23.3-mile aqueduct that carries the water under the Continental Divide, as deep as 4,500 feet below the spine of the continent.

In Park County, the water empties into the South Platte River, feeding the Front Range Reservoirs that have enabled Denver to grow into a thriving metropolis at the cusp of the Great Plains and Rocky Mountains. Water diverted from the Blue River Basin in Summit County provides nearly 40 percent of Denver Water’s supply. Continue reading

Dillon Reservoir generally stable in winter months

Cold-season operations vary depending on water, maintenance needs

Ice flowers grow in early December on the surface of Dillon Reservoir while the ice is still thin. PHOTO BY BOB BERWYN.

By Bob Berwyn

SUMMIT COUNTY — During the summer, water watchers keep a close eye on Dillon Reservoir. The water level in the impoundment is critical to the area’s recreation economy and also to downstream fisheries.

But what happens during the cold winter season, when the reservoir rests under a layer of ice? Does the level go up or down? Is water being diverted to the Front Range from under the ice?

To answer those questions, I spoke with Bob Steger, Denver Water’s manager of raw water supplies. Steger is point person for Denver Water in the spring, when Silverthorne wants to know if there’s going to be flooding, and as local marina operators gear up for the boating season. Continue reading

Denver Water: Roberts Tunnel off through April 2011

The Roberts Tunnel, a key link in Denver Water's supply system, took about 16 years to build. PHOTO COURTESY DENVER WATER. Click on the photo to visit Denver Water's online gallery of historic water project photos.

Major maintenance of valves at east end, near Grants, will take several months to complete

By Bob Berwyn

SUMMIT COUNTY — The trans-mountain Roberts Tunnel, which transports water from Dillon Reservoir to the South Platte drainage, will remain shut off until April while Denver Water does major maintenance on the valves at the east end of the underground aqueduct.

The 23-mile tunnel under the Continental Divide was completed in 1962. It’s often shut down in the fall for shorter periods of time for regular maintenance, but this year’s project required a longer closure, said Bob Steger, Denver Water’s manager of raw water resources. Continue reading

Dillon Reservoir water level starting to drop

The water level in Dillon Reservoir, seen here from near Heaton Bay during sunset July 12, is starting to drop as Denver Water diverts through the Roberts Tunnel.

Denver Water taking 375 cfs through Roberts Tunnel, inflow only at 177 cfs as local streams drop toward historic low flows


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By Bob Berwyn

SUMMIT COUNTY — After quickly filling up in late May, Dillon Reservoir is starting to drop as Denver Water draws significant quantities of water through the Roberts Tunnel.

As of July 19, about 375 cubic feet per second were being diverted under the Continental Divide to the South Platte drainage.

“It’s been really hot in Denver,” said water resource project manager Dave Bennett, “Demand is up.” Continue reading

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